Objective Limbic encephalitis with leucine-rich glioma inactivated 1 (LGI1) protein autoantibodies is associated with cognitive impairment, psychiatric symptoms, and seizures, including faciobrachial dystonic seizures (FBDS). Patient-derived LGI1-autoantibodies cause isolated symptoms of memory deficits in mice and seizures in rats. Using a multimodal experimental approach, we set out to improve the validity of existing in vivo rodent models to further recapitulate the full clinical syndrome of anti-LGI1 antibody mediated disease. Methods A monoclonal anti-LGI1 antibody (anti-LGI1 mAb) derived from a patient’s CSF antibody-secreting cell was infused intracerebroventricularly (ICV) into rats and mice for one or two weeks, respectively. Cellular excitability of CA3 pyramidal neurons was determined in hippocampal slices. Structural changes in mouse brains were explored using MRI. Antibody effects on behavior and brain activity of rats were studied using video-EEG. Results Anti-LGI1 mAbs augmented the excitability of CA3 pyramidal neurons and elicited convulsive and non-convulsive spontaneous epileptic seizures in mice and rats. Mice displayed a hypoactive and anxious phenotype during behavioral testing. MRI revealed acutely increased hippocampal volume after ICV anti-LGI1 mAb infusion. Video-EEG recordings of juvenile rats uncovered two peaks of seizure frequency during the 7-day antibody infusion period resembling the natural progression of seizures in human anti-LGI1 encephalitis. Interpretation Our data strongly corroborate and extend our understanding of the direct pathogenic and epileptogenic role of human LGI1 autoantibodies.

OBJECTIVE:Paediatric autoimmune encephalitis and acute disseminated encephalomyelitis (ADEM) are neuroinflammatory disorders that can cause acute MRI abnormalities. Recent analyses suggest brain volume reductions months to years after disease onset. This study aimed to verify whether decreased gray matter thickness would also be observed in whole-brain cortical thickness as well as in temporal polar and orbitofrontal cortices. METHODS:A cohort of children previously diagnosed with autoimmune encephalitis (including anti-NMDA encephalitis and ADEM) were recruited at least two years after initial presentation and a cohort of typically developing children with no known neurological conditions. Cortical thickness across the whole-brain and in each region-of-interest was measured from T1w MRI scans using Freesurfer. RESULTS:MRI scans from 12 children with autoimmune encephalitis (mean age = 10.5; 8F:4M) and 48 controls (mean age = 10.7; 23F 25M) were analysed. The autoimmune encephalitis group had lower cortical thickness in a cluster covering the top part of the left superior occipital gyrus and the bottom part of the left superior parietal lobule (cluster size = 681.55 mm2; corrected cluster-wise p = .00459; cluster-wise Cohen's d = -8.3773). No multivariate effect on the cortical thickness of the regions-of-interest was found (Roy's Largest Root = .095, F(df) = 1.207(4); p = .319; partial η2 = .087). A small univariate effect was observed, with autoimmune encephalitis predicting lower left orbitofrontal thickness (F = 4.407, p = .040, Partial η2 = .075). INTERPRETATION:Children with autoimmune encephalitis may be subject to local cortical thinning in the long term.

Purpose: Research into epilepsy has experienced decades of chronic underfunding compared to other neurological conditions despite its prevalence and seriousness. To evidence the need for greater investment, the Epilepsy Research Institute (formerly Epilepsy Research UK) funded, led and managed a James Lind Alliance (JLA) Priority Setting Partnership (PSP). This “industry standard” methodology brings together healthcare professionals, patients, carers and patient group representatives to identify and prioritise research uncertainties within a defined area of health or care.Methods: The UK Epilepsy PSP is a once-in-a-generation, national consensus that collated and ranked the research priorities of the UK epilepsy and associated condition community. Following JLA methodology, this 18-month project engaged over 100 patient groups and 5,000 people affected by and working in epilepsy, including medics and allied healthcare professionals, from across the UK.Results: Over 5,400 priorities were received, with anti-seizure medication, sudden unexpected death in epilepsy (SUDEP) and epilepsy in women among the most frequently reported themes. The responses received were categorised and translated into distinct, researchable questions. Questions were excluded if deemed to be “answered” following an evidence check, while research uncertainties (i.e. unanswered and partially answered questions) formed the basis of a second, shortlisting survey. The shortlisted questions were then discussed and debated at the final workshop by participants that broadly represented the UK epilepsy and associated condition community. The final ranking and Top Ten priorities for research into epilepsy were then agreed.Conclusion: The aim of the UK Epilepsy PSP is to encourage and inspire researchers to investigate the research areas prioritised by those most affected by the condition and provide the evidence of need to aid future policy making discussions and support research funding applications.

BACKGROUND AND OBJECTIVES:Paramagnetic rim lesions (PRLs), visible on susceptibility-based imaging (SbI), reflect chronic active inflammation in multiple sclerosis (MS). In adult-onset MS, PRLs are associated with a more aggressive disease course.The objectives of this study were to assess the prevalence of PRLs in children with MS and to examine how baseline PRL count relates to clinical disability and brain tissue volume loss, both cross-sectionally and over short-term follow-up. METHODS:We retrospectively analyzed pediatric patients from 4 UK tertiary neuroimmunology centers who met the 2017 McDonald diagnostic criteria and had 3D T1-weighted, T2-weighted, fluid-attenuated inversion recovery, and SbI MRI available. PRLs were identified per North American Imaging in MS criteria and anatomically classified. Brain volumes were segmented using Mindglide, with z-scores derived from NIH normative data. Associations between baseline PRL burden, clinical variables, and brain volumes were assessed using univariable and multivariable stepwise regression. Linear mixed-effects models evaluated the predictive value of baseline PRL burden on longitudinal brain volume changes. RESULTS:Fifty-four patients (mean age 14.0 ± 2.2 years; 75.9% female) were included. At least 1 PRL was seen in 74.1% of patients, with a median number of 2 PRLs (interquartile range [IQR] = 0-6), predominantly in periventricular regions, and accounting for 25% of total T2-weighted hyperintense lesions. In multivariable Poisson regression, at baseline, shorter disease duration (incidence rate ratio [IRR] = 0.987, 95% CI 0.975-0.999, p = 0.035), and greater number (IRR 1.045, 95% CI 1.035-1.054, p < 0.001) and volume (IRR 1.018, 95% CI 1.004-1.032, p = 0.012) of T2-hyperintense lesions were associated with higher PRL count. Cross-sectionally, a higher PRL count was associated with lower cortical (β = -0.139, 95% CI -0.231 to -0.047, p = 0.016) and deep (β = -0.096, 95% CI -0.166 to -0.026, p = 0.032) gray matter volume z-scores. No significant association was observed between clinical disability and PRL count. In 45 patients followed up for a median 17 months (IQR 12-24), a higher baseline PRL count predicted greater deep gray matter volume loss over time (β = -0.020, 95% CI -0.034 to -0.006, p = 0.036). DISCUSSION:PRLs are common in pediatric MS and are linked to greater lesion burden and gray matter atrophy. These findings suggest that PRLs are promising imaging biomarkers of more severe brain tissue damage although their ability to predict future disability requires confirmation in longer term studies.

This cohort study examines the association between slowly expanding lesions and pediatric-onset multiple sclerosis among younger individuals, focusing on brain growth and disability progression.

Background Lesion resolution is often observed in children with myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD), and asymptomatic lesions are less commonly reported in MOGAD than in multiple sclerosis (MS). Objective We aimed to evaluate brain MRI changes over time in paediatric MOGAD. Methods Retrospective study in eight UK paediatric neuroscience centres. Acute brain MRI and available follow-up MRIs were reviewed. Predictors for lesion dynamic were evaluated using multivariable regression and Kaplan-Meier survival analyses were used to predict risk of relapse, disability and MOG-Ab status. Results 200 children were included (MOGAD 97; MS 103). At first MRI post attack, new symptomatic and asymptomatic lesions were seen more often in MS versus MOGAD (52/103 vs 28/97; p=0.002 and 37/103 vs 11/97; p<0.001); 83% of patients with MOGAD showed at least one lesion’s resolution at first follow‐up scan, and 23% had normal MRI. Only 1 patient with MS had single lesion resolution; none had normal MRI. Disappearing lesions in MOGAD were seen in 40% after the second attack, 21% after third attack and none after the fourth attack. New lesions at first follow-up scan were associated with increased likelihood of relapse (p=0.02) and persistent MOG-Ab serostatus (p=0.0016) compared with those with no new lesions. Plasma exchange was associated with increased likelihood of lesion resolution (p=0.01). Longer time from symptom onset to steroids was associated with increased likelihood of new lesions; 50% increase at 20 days (p=0.01). Conclusions These striking differences in lesion dynamics between MOGAD and MS suggest greater potential to repair. Early treatment with steroids and plasma exchange is associated with reduced likelihood of new lesions.

Anti-contactin associated protein receptor 2 (CASPR2) encephalitis is a severe autoimmune encephalitis with a variable clinical phenotype including behavioral abnormalities, cognitive decline, epileptic seizures, peripheral nerve hyperexcitability and neuropathic pain. The detailed mechanisms of how CASPR2 autoantibodies lead to synaptic dysfunction and clinical symptoms are largely unknown. Aiming for analyses from the molecular to the clinical level, we isolated antibody-secreting cells from the cerebrospinal fluid of two patients with CASPR2 encephalitis. From these we cloned four anti-CASPR2 human monoclonal autoantibodies (mAbs) with strong binding to brain and peripheral nerves. All were highly hypermutated and mainly of the IgG4 subclass. Mutagenesis studies determined selective binding to the discoidin domain of CASPR2. Surface plasmon resonance revealed affinities with dissociation constants KD in the pico- to nanomolar range. CASPR2 mAbs interrupted the interaction of CASPR2 with its binding partner contactin 2 in vitro and were internalized after binding to CASPR2-expressing cells. Electrophysiological recordings of rat hippocampal slices after stereotactic injection of CASPR2 mAbs showed characteristic afterpotentials following electrical stimulation. In vivo experiments with intracerebroventricular administration of human CASPR2 mAbs into mice and rats showed EEG-recorded brain hyperexcitability but no spontaneous recurrent seizures. Behavioral assessment of infused mice showed a subtle clinical phenotype, mainly affecting sociability. Mouse brain MRI exhibited markedly reduced resting-state functional connectivity without short-term structural changes. Together, the experimental data support the direct pathogenicity of CASPR2 autoantibodies. The minimally invasive EEG and MRI techniques applied here may serve as novel objective, quantifiable tools for improved animal models, in particular for subtle neuropsychiatric phenotypes or repeated measurements.

OBJECTIVES:We aimed to study the risks of relapse and long term disability in children with non-MS acquired demyelinating syndromes (ADS). METHODS:In this prospective, multi-centre study, from the 14 UK pediatric neurology centres, children (<16 years) experiencing a first episode of ADS were recruited from 2010 to 2014. Case report forms were collected prospectively. RESULTS:A total of 269 children were recruited and followed up for a median of 7.2 years. Median age at onset was 9y (IQR 9.5-14.5, 126 females). At last follow-up, 46 (18 %) had MS, 4 AQP4-Ab NMOSD and 206 (80 %) had other ADS, of which 27 (13 %) relapsed. Relapsing MOGAD was the diagnosis in 12/27, 6 were seronegative and 9 did not have antibodies tested. Frequency of relapse differed according to first presentation in non-MS ADS, being least likely in transverse myelitis (p = 0.025). In the non-MS group, MOG-Ab was predictive of relapse (HR = 8.42; p < 0.001) occurring 8 times as often decreasing over time. Long-term difficulties did not differ between children with monophasic vs relapsing diseases. CONCLUSION:The risk of relapse in non-MS ADS depends on initial diagnosis, and MOG-Ab positivity. Long-term difficulties are observed regardless of relapses and are determined by presenting phenotype.

One striking clinical hallmark in patients with autoantibodies to leucine-rich glioma inactivated 1 (LGI1) is the very frequent focal seizure semiologies, including faciobrachial dystonic seizures (FBDS), in addition to the amnesia. Polyclonal serum IgGs have successfully modelled the cognitive changes in vivo but not seizures. Hence, it remains unclear whether LGI1-autoantibodies are sufficient to cause seizures. We tested this with the molecularly precise monoclonal antibodies directed against LGI1 [LGI1-monoclonal antibodies (mAbs)], derived from patient circulating B cells. These were directed towards both major domains of LGI1, leucine-rich repeat and epitempin repeat, and infused intracerebroventricularly over 7 days into juvenile male Wistar rats using osmotic pumps. Continuous wireless EEG was recorded from a depth electrode placed in hippocampal CA3 plus behavioural tests for memory and hyperexcitability were performed. Following infusion completion (Day 9), post-mortem brain slices were studied for antibody binding and effects on Kv1.1. The LGI1-mAbs bound most strongly in the hippocampal CA3 region and induced a significant reduction in Kv1.1 cluster number in this subfield. By comparison to control-Ab injected rats video-EEG analysis over 9 days revealed convulsive and non-convulsive seizure activity in rats infused with LGI1-mAbs, with a significant number of ictal events. Memory was not impaired in the novel object recognition test. Peripherally-derived human LGI1-mAbs infused into rodent CSF provide strong evidence of direct in vivo epileptogenesis with molecular correlations. These findings fulfill criteria for LGI1-antibodies in seizure causation.

Paediatric autoimmune encephalitis (e.g., acute disseminated encephalomyelitis, N-methyl-D-aspartate receptor antibody encephalitis) is an inflammatory brain disease that causes cognitive deficits, psychiatric symptoms, seizures, MRI, and EEG abnormalities. Patients can continue to experience residual cognitive difficulties months to years after the acute illness. Magnetoencephalography (MEG) can examine neural changes in the absence of frank structural abnormalities and may help identify factors predicting children at risk of long-term cognitive deficits. We predicted that theta and delta brain functional connectivity networks would be associated with processing speed and working memory in children with autoimmune encephalitis. Participants were children diagnosed with autoimmune encephalitis at least 18 months before testing and typically developing children. All completed MEG recording (Elekta Neuromag Triux) at rest, eyes open with a fixation cross during six minutes; T1 MRI scans; and cognitive evaluation using the primary subtests of the Weschler Intelligence Scale for Children, fifth edition. Brain connectivity, specifically in delta and theta brain activity, was estimated with amplitude envelope correlation, and network efficiency was measured using graph measures (global efficiency, local efficiency, modularity). The measures were compared across the two groups with permutation correction for multiple thresholds. Finally, statistical associations with processing speed and working memory scores were tested in the autoimmune encephalitis group. Age and sex-matched cohorts of 12 children with AE (11.2+/-3.5y, IQR 9y; 5M:7F) and 12 typically developing controls (10.6+/-3.2y, IQR 7y; 8M:4F) participated in this study. On average, children with autoimmune encephalitis did not differ from controls in working memory (t(21)= 1.449; p = .162; d = 0.605) but had a significantly lower processing speed (t(21) = 2.463; p = .023; Cohens d = 1.028). The groups did not differ in theta network topology measures but the autoimmune encephalitis group had a significantly lower delta local efficiency across all thresholds tested (d = -1.60 at network threshold 14%). Theta modularity was associated with lower working memory (β = -.781; t(8) = -2.588, p = .032) but this effect did not survive correction for multiple comparisons (p(corr) = .224). No other graph measure was significantly associated with psychometric scores in the autoimmune encephalitis group. MEG was able to capture network alterations in paediatric autoimmune encephalitis patients, specifically in the topological organisation of delta brain activity. This preliminary study demonstrates that MEG is an appropriate tool for assessing children with autoimmune encephalitis; future studies should focus on confirming which functional networks can predict cognitive performance.

IntroductionNew onset refractory status epilepticus (NORSE) is a rare and devastating condition characterised by the sudden onset of refractory status epilepticus (RSE) without an identifiable acute or active structural, toxic, or metabolic cause in an individual without a pre-existing diagnosis of epilepsy. Febrile infection-related epilepsy syndrome (FIRES) is considered a subcategory of NORSE and presents following a febrile illness prior to seizure onset. NORSE/FIRES is associated with high morbidity and mortality in children and adults.Methods and resultsIn this review we first briefly summarise the reported clinical, paraclinical, treatment and outcome data in the literature. We then report on existing knowledge of the underlying pathophysiology in relation to in vitro and in vivo pre-clinical seizure and epilepsy models of potential relevance to NORSE/FIRES.DiscussionWe highlight how pre-clinical models can enhance our understanding of FIRES/NORSE and propose future directions for research.

Paediatric acquired demyelinating syndromes (pADS) attack white matter pathways in the brain during an important period of development. Affected children can experience poor functional outcomes, including deficits in specific cognitive domains. Understanding risk factors for poor outcome will guide clinical management of these children. One clinical phenotype which may differentially impact cognitive outcomes is the presence of autoantibodies to myelin oligodendrocyte glycoprotein (MOG). Preliminary research has suggested that cognitive difficulties exist in paediatric patients who test positive for MOG antibodies or MOGAD (Myelin Oligodendrocyte Glycoprotein Associated Disease) however, they experience a less severe profile compared to seronegative counterparts. The current study assesses children diagnosed with pADS who tested positive or negative for MOG-ab using standardised assessments of both intellectual functioning and academic ability. The results show that a subset of MOGAD patients experience clinically significant sequalae in intellectual functioning and academic ability. The neuropsychological profile also differed between children with and without MOG-ab positivity, with seronegative patients more likely to show a clinically relevant difficulties at the individual patient level. Whilst no differences existed at the group-level; the current study demonstrates the relative additional risk of intellectual / academic difficulty associated with MOG-ab seronegativity. This research further supports the growing perspective that MOG-positivity confers a more favourable neuropsychological outlook than is the case for their seronegative counterparts. This broadening consensus offers reassurance for clinicians, families, and patients.

Background and Objectives Antibodies to myelin oligodendrocyte glycoprotein (MOG-Ab) have recently been reported in patients with encephalitis who do not fulfill criteria for acute disseminated encephalomyelitis (ADEM). We evaluated a cohort of these children and compared them with children with ADEM. Methods This retrospective, multicenter cohort study comprised consecutive patients <18 years of age with MOG-Ab who fulfilled criteria for autoimmune encephalitis. These patients were stratified into (1) children not fulfilling criteria for ADEM (encephalitis phenotype) and (2) children with ADEM. Clinical/paraclinical data were extracted from the electronic records. Comparisons were made using the Mann-Whitney U test and chi 2 Fisher exact test for statistical analysis. Results From 235 patients with positive MOG-Ab, we identified 33 (14%) with encephalitis and 74 (31%) with ADEM. The most common presenting symptoms in children with encephalitis were headache (88%), seizures (73%), and fever (67%). Infective meningoencephalitis was the initial diagnosis in 67%. CSF pleocytosis was seen in 79%. Initial MRI brain was normal in 8/33 (24%) patients. When abnormal, multifocal cortical changes were seen in 66% and unilateral cortical changes in 18%. Restricted diffusion was demonstrated in 43%. Intra-attack new lesions were seen in 7/13 (54%). When comparing with children with ADEM, children with encephalitis were older (median 8.9 vs 5.7 years, p = 0.005), were more likely to be admitted to intensive care (14/34 vs 4/74, p < 0.0001), were given steroid later (median 16.6 vs 9.6 days, p = 0.04), and were more likely to be diagnosed with epilepsy at last follow-up (6/33 vs 1/74, p = 0.003). Discussion MOG-Ab should be tested in all patients with suspected encephalitis even in the context of initially normal brain MRI. Although exclusion of infections should be part of the diagnostic process of any child with encephalitis, in immunocompetent children, when herpes simplex virus CSF PCR and gram stains are negative, these features do not preclude the diagnosis of immune mediated disease and should not delay initiation of first-line immunosuppression (steroids, IVIG, plasma exchange), even while awaiting the antibody results.

Objective: The aim of this study was to evaluate the efficacy and safety of ocrelizumab treatment for pediatric-onset Multiple Sclerosis (POMS) in a real-world clinical setting. Background: There is a growing consensus favouring earlier use of highly effective disease modifying therapies (DMTs) in POMS. Design/Methods: We conducted a prospective study including consecutive POMS (<18 years) from three UK tertiary paediatric neurosciences centers who received ocrelizumab. Results: We included a total of 60 POMS patients; 49 female (81.7%), 41 non-white (68.3%), median age 14.6 yrs (IQR 13.3, 15.5). Median follow-up period was 1.0 yr (range, 0.1–2.6). Forty-three patients (71.7%) had ocrelizumab as their first DMT. The median number of relapses per patient pre-treatment was 2 (range 1–5). Two patients relapsed within one month of starting ocrelizumab and 1 patient had an optic neuritis 6-months post ocrelizumab initiation. During the follow-up period, a median of 2 (range 1–5) repeated MRI scans were performed (total scans, n=140). Forty out of 43 (93.0%) patients achieved no evidence of disease activity (NEDA-3) at 12-months follow-up; two patients had one new brain lesion each at 6-months and a different patient had a relapse (optic neuritis) without new brain lesions at 6-months post treatment. Median EDSS score remained stable during follow-up; 1.0 at baseline and follow-up (p=0.21). In addition, there was no change in cognitive measures at follow-up; baseline SDMT mean score 46 vs follow-up SDMT mean score 48 (p=0.39). The most common adverse events reported were infusion-related-reactions (33/60, 55%), all of which were grade 1 or 2. Serious adverse events were recorded in one patient with enterovirus meningitis, who made a full recovery. Conclusions: This study confirms that ocrelizumab, which is proven efficacious for adults with MS, is also effective in POMS with a comparable safety profile. Assessment for long-term efficacy and safety is ongoing. Disclosure: Dr. Abdel-Mannan has nothing to disclose. Arman Eshaghi has nothing to disclose. Dr. Champsas has nothing to disclose. Kshitij Mankad has nothing to disclose. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Roche. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Biogen. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for EMD Serono. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Sanofi. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Novartis. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Janssen. Dr. Brownlee has received personal compensation in the range of $500-$4,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Sage. Dr. Rossor has nothing to disclose. Sukhvir Wright has nothing to disclose. Dr. Wassmer has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Biogen. The institution of Dr. Wassmer has received research support from Birmingham Children's Hospital Charity Research Foundation. The institution of Cheryl Hemingway has received personal compensation in the range of $0-$499 for serving as a Consultant for Biogen. The institution of Cheryl Hemingway has received personal compensation in the range of $0-$499 for serving as a Consultant for Novartis. The institution of Cheryl Hemingway has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UCB. The institution of Cheryl Hemingway has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Sanofi. The institution of Cheryl Hemingway has received research support from Medical research Committee. Ming Lim has nothing to disclose. Prof. Ciccarelli has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Novartis. Prof. Ciccarelli has received personal compensation in the range of $0-$499 for serving on a Speakers Bureau for Merck. Prof. Ciccarelli has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for NEUROLOGY Journal. Dr. Hacohen has nothing to disclose.